// The byte helpers: hexadecimal, comparison, UTF-8 as strict as Go's, Go's
// utf8.DecodeRune and Go's %q, as bytes.test.ts of datekeys-ts. The texts of
// %q are those printed by Go 1.26.

import 'dart:convert';
import 'dart:typed_data';

import 'package:crypto/crypto.dart';
import 'package:datekeys/src/bytes.dart';
import 'package:test/test.dart';

// One backslash, for the texts of Go's %q.
const bs = '\\';

String cp(List<int> runes) => String.fromCharCodes(runes);

void main() {
  test('converts hexadecimal', () {
    expect(toHex([0, 1, 0xab, 0xff]), '0001abff');
    expect(toHex([]), '');
    expect(fromHex('0001ABff'), [0, 1, 0xab, 0xff]);
    expect(fromHex(''), isEmpty);
    expect(() => fromHex('abc'), throwsFormatException);
    expect(() => fromHex('zz'), throwsFormatException);
    expect(() => fromHex('0g'), throwsFormatException);
    expect(() => fromHex('${cp([0xff10])}0'), throwsFormatException);
  });

  test('compares and joins byte strings', () {
    final a = [1, 2];
    expect(equalBytes(a, [1, 2]), isTrue);
    expect(equalBytes(a, [1, 3]), isFalse);
    expect(equalBytes(a, [1]), isFalse);
    expect(compareBytes(a, [1, 2]), 0);
    expect(compareBytes(a, [1, 3]), -1);
    expect(compareBytes([2], a), 1);
    expect(compareBytes([1], a), -1);
    expect(compareBytes(a, [1]), 1);
    expect(compareBytes([0xff], [0x00, 0x00]), 1);
    expect(
      concatBytes([
        a,
        <int>[],
        Uint8List.fromList([3]),
      ]),
      [1, 2, 3],
    );
    expect(concatBytes([]), isEmpty);
  });

  group('UTF-8', () {
    // Each byte string that UTF-8 forbids, and what Go's utf8.Valid refuses.
    final invalid = <String, List<int>>{
      'an invalid byte': [0x61, 0xff],
      'a byte above F4': [0xf5, 0x80, 0x80, 0x80],
      'an overlong NUL': [0xc0, 0x80],
      'an overlong three-byte form': [0xe0, 0x80, 0x80],
      'an overlong four-byte form': [0xf0, 0x80, 0x80, 0x80],
      'an encoded high surrogate': [0xed, 0xa0, 0x80],
      'an encoded low surrogate': [0xed, 0xbf, 0xbf],
      'a code point above U+10FFFF': [0xf4, 0x90, 0x80, 0x80],
      'a truncated sequence': [0xe2, 0x82],
      'a lone continuation byte': [0x80],
    };

    test('dart:convert refuses what Go refuses, and so does decodeUtf8', () {
      for (final MapEntry(key: name, value: b) in invalid.entries) {
        // Short inputs and long ones: dart2js decodes the long ones with the
        // TextDecoder of the platform.
        for (final input in [
          b,
          [...b, ...List.filled(40, 0x61)],
        ]) {
          expect(
            () => const Utf8Decoder().convert(input),
            throwsFormatException,
            reason: name,
          );
          expect(decodeUtf8(input), isNull, reason: name);
          expect(isValidUtf8(input), isFalse, reason: name);
        }
      }
    });

    test('dart:convert drops a leading U+FEFF, and decodeUtf8 keeps it', () {
      // The reason decodeUtf8 does not use Utf8Decoder: a text that starts
      // with U+FEFF would decode as one that does not, on the VM and on the
      // web alike.
      for (final rest in [
        [0x61],
        List.filled(40, 0x61),
      ]) {
        final input = [0xef, 0xbb, 0xbf, ...rest];
        expect(const Utf8Decoder().convert(input), cp(rest));
        expect(decodeUtf8(input), cp([0xfeff, ...rest]));
      }
      // Further ones are characters for both.
      expect(
        decodeUtf8([0x61, 0xef, 0xbb, 0xbf, 0xef, 0xbb, 0xbf]),
        cp([0x61, 0xfeff, 0xfeff]),
      );
      expect(
        decodeUtf8([0xef, 0xbb, 0xbf, 0xef, 0xbb, 0xbf]),
        cp([0xfeff, 0xfeff]),
      );
    });

    test('decodes every valid sequence, U+FFFD and U+10FFFF included', () {
      final valid = <List<int>, String>{
        []: '',
        [0x00]: cp([0]),
        [0x7f]: cp([0x7f]),
        [0xc2, 0x80]: cp([0x80]),
        [0xdf, 0xbf]: cp([0x7ff]),
        [0xe0, 0xa0, 0x80]: cp([0x800]),
        [0xed, 0x9f, 0xbf]: cp([0xd7ff]),
        [0xee, 0x80, 0x80]: cp([0xe000]),
        [0xef, 0xbf, 0xbd]: cp([0xfffd]),
        [0xf0, 0x90, 0x80, 0x80]: cp([0x10000]),
        [0xf4, 0x8f, 0xbf, 0xbf]: cp([0x10ffff]),
      };
      for (final MapEntry(key: b, value: s) in valid.entries) {
        expect(decodeUtf8(b), s, reason: toHex(b));
        expect(isValidUtf8(b), isTrue, reason: toHex(b));
        expect(utf8Bytes(s), b, reason: toHex(b));
      }
    });

    test('writes a well-formed string as dart:convert does', () {
      final s = cp([0xfeff, 0x61, 0xe9, 0x20ac, 0x10000, 0x1f600, 0x10ffff]);
      expect(utf8Bytes(s), utf8.encode(s));
      expect(isWellFormedUtf16(s), isTrue);
    });

    test(
      'writes a lone surrogate in generalized UTF-8, which is not UTF-8',
      () {
        // dart:convert writes U+FFFD in its place: the string would encode as
        // another.
        expect(utf8.encode(cp([0xd800])), [0xef, 0xbf, 0xbd]);
        final cases = <List<int>, String>{
          [0xd800]: 'eda080',
          [0xdfff]: 'edbfbf',
          [0x61, 0xdc00, 0xd800]: '61edb080eda080',
          [0xd800, 0xd800, 0xdc00]: 'eda080f0908080',
          [0xdbff, 0x61]: 'edafbf61',
        };
        for (final MapEntry(key: units, value: hex) in cases.entries) {
          final s = cp(units);
          expect(toHex(utf8Bytes(s)), hex);
          expect(isWellFormedUtf16(s), isFalse);
          expect(isValidUtf8(utf8Bytes(s)), isFalse);
        }
      },
    );

    test('decodes runes as Go utf8.DecodeRune', () {
      final b = [
        0x41, 0xc3, 0xa9, 0xe2, 0x82, 0xac, 0xf0, 0x9f, //
        0x98, 0x80, 0xc0, 0x80, 0xe0, 0x80, 0xf5,
      ];
      expect(decodeRune(b, 0), (0x41, 1));
      expect(decodeRune(b, 1), (0xe9, 2));
      expect(decodeRune(b, 3), (0x20ac, 3));
      expect(decodeRune(b, 6), (0x1f600, 4));
      for (final i in [7, 10, 11, 12, 13, 14]) {
        expect(decodeRune(b, i), (0xfffd, 1), reason: '$i');
      }
      expect(decodeRune(b, 15), (0xfffd, 0));
      expect(decodeRune([0xf0, 0x9f, 0x98], 0), (0xfffd, 1));
      expect(decodeRune([0xc3], 0), (0xfffd, 1));
      expect(decodeRune([0xef, 0xbf, 0xbd], 0), (0xfffd, 3));
      expect(decodeRune([], 0), (0xfffd, 0));
    });
  });

  group("Go's %q", () {
    test('quotes as strconv.Quote', () {
      expect(
        goQuote([0x61, 0x00, 0x62, 0xff, 0xc3, 0xa9, 0xe2, 0x80, 0xa8]),
        '"a${bs}x00b${bs}xff${cp([0xe9])}${bs}u2028"',
      );
      expect(
        goQuote(utf8Bytes(cp([7, 8, 12, 10, 13, 9, 11]))),
        '"${bs}a${bs}b${bs}f${bs}n${bs}r${bs}t${bs}v"',
      );
      expect(goQuote(utf8Bytes('"$bs')), '"$bs"$bs$bs"');
      expect(
        goQuote(utf8Bytes(cp([0x10000, 0x1f600, 0x301]))),
        '"${cp([0x10000, 0x1f600, 0x301])}"',
      );
      expect(
        goQuote(utf8Bytes(cp([0xa0, 0xfeff, 0xe000, 0x10ffff, 0x7f]))),
        '"${bs}u00a0${bs}ufeff${bs}ue000${bs}U0010ffff${bs}x7f"',
      );
      expect(
        goQuote([0xed, 0xa0, 0x80, 0xf4, 0x90, 0x80, 0x80, 0xe2, 0x82]),
        '"${bs}xed${bs}xa0${bs}x80${bs}xf4${bs}x90${bs}x80${bs}x80${bs}xe2'
        '${bs}x82"',
      );
      expect(goQuote(utf8Bytes(cp([0xfffd]))), '"${cp([0xfffd])}"');
      expect(goQuote(utf8Bytes(cp([0x378]))), '"${bs}u0378"');
      expect(goQuote([]), '""');
      // New in Unicode 16, which the platform may know and Go 1.26 does not.
      expect(
        goQuote(utf8Bytes(cp([0x31e4, 0x31e3, 0x1fbcb, 0x1fbca]))),
        '"${bs}u31e4${cp([0x31e3])}${bs}U0001fbcb${cp([0x1fbca])}"',
      );
      // A lone surrogate, as its generalized UTF-8.
      expect(
        goQuote(utf8Bytes(cp([0x61, 0xd800]))),
        '"a${bs}xed${bs}xa0${bs}x80"',
      );
    });

    test("classifies every rune as Go 1.26's strconv.IsPrint", () {
      // The IsPrint bit set of all runes (bit r at byte r >> 3, mask
      // 1 << (r & 7)) and its SHA-256, computed by Go 1.26.8 (Unicode
      // 15.0.0), as bytes.test.ts pins it.
      final bits = Uint8List(0x110000 ~/ 8);
      var runes = 0;
      var ranges = 0;
      var previous = false;
      for (var r = 0; r < 0x110000; r++) {
        final p = isPrint(r);
        if (p) {
          bits[r >> 3] |= 1 << (r & 7);
          if (r >= 0x80) {
            runes++;
            if (!previous) ranges++;
          }
        }
        previous = p && r >= 0x80;
      }
      expect((runes, ranges), (148903, 710));
      expect(
        sha256.convert(bits).toString(),
        'dbe4beecc0027b38c16c32d304958e611e27baa40412efea4cf616346eb631a2',
      );
      for (final r in [
        0x80,
        0x9f,
        0xa0,
        0xad,
        0x31e4,
        0xe000,
        0xfeff,
        0x10ffff,
      ]) {
        expect(isPrint(r), isFalse, reason: r.toRadixString(16));
      }
      for (final r in [
        0x20,
        0x7e,
        0xa1,
        0xe9,
        0x31e3,
        0xfffd,
        0x1f600,
        0xe0100,
      ]) {
        expect(isPrint(r), isTrue, reason: r.toRadixString(16));
      }
      for (final r in [0x00, 0x1f, 0x7f]) {
        expect(isPrint(r), isFalse, reason: r.toRadixString(16));
      }
    });
  });
}